Carburetor



May 1937. E E. SKRIWAN 2,079,306

NEEDLE FOR TAKING-UP DROPPED STITCHES Filed Aug. 6, 1956 j eufr Sir/wan@7 M ma WM Patented June 22, 1937 .UNITIED STATES PATENT OFFICEApplication May 31, 1932, Serial No. 614,520

8 Claims.

This invention relates to carburetors and par ticularly to improvedapparatus thereof, known as pick-up mechanism, for temporarilyaugmenting the supply of fuel to the fuel mixture passage of acarburetor.

Fuel feeding apparatus of this character is preferably operated in timedrelation with the throttle of the carburetor so as to normally increasethe supply of fuel to the fuel mixture passage 1 thereof as the throttleis opened. This may be conveniently accomplished by mechanicallyoperating the piston of the pick-up pump by the throttle controlmechanism, but with conventional pumps of this character the action ofthe throttle valve is seriously impeded and the force required of theoperator to open the throttle valve is excessively increased by theresistance of the pump. Attempts to overcome this slowing down of thethrottle action by merely interposing yieldable members between thepiston of the pump and the throttle control mechanism have resulted inintolerable delay in the discharging of the pick-up fuel charge. Whenthis occurs the fuel mixture becomes too lean to produce the powerrequired for acceleration of an engine. If

the pick-up discharge is discontinued immediately upon opening of thethrottle the fuel ratio of the mixture is also reduced below thatrequired for acceleration.

The main objects of this invention are to provide a pick-up pump in acarburetor which can be operated by the throttle control mechanismthereof without either impeding the throttle action or excessivelyincreasing the force required 35 to operate the throttle valve; toprovide a pump of this character which immediately discharges fuelduring the opening of the throttle and which continues to discharge fuelfor a predetermined period after the throttle is at rest in an opened 40position; to provide a fuel displacing member in the pump cylinder whichoccupies less than the full cross-sectional area thereof and which isadapted to move freely through the contents of the pump cylinder; and toprovide positive act- 45 ing mechanism for actuating the free movingfuel displacing member in unison with the movement of the throttlecontrol apparatus so as to initially discharge fuel from the pumpcylinder simultaneously with the opening of the throttle valve.

Other objects of the invention are to provide a close-fitting fueldisplacing member in the cylinder of a pick-up pump which is movablerel- 55 ative to the freely movable fuel displacing member and relativeto the positive acting mechanism thereof; and to provide a yieldablemember for moving the close-fitting member through its fuel dischargingstroke which is operable by the positive acting actuating mechanism toimpart to the close-fitting member a delayed action that continues afterthe throttle is at rest in an open position.

Further objects of the invention are to provide an improved liquid fuelconveying system in a carburetor having pick-up mechanism of the abovecharacter; to provide self-acting valves in a fuel system of this kindfor cutting off the return flow of fuel to the fuel reservoir of thecarburetor during the discharge strokes of the pistons in the pick-uppump and which also prevent the withdrawal of fuel from the normal fuelnozzle of the carburetor during the loading strokes of the pump; toprovide a metering device in the fuel system which is calibrated topredetermine the period of duration of the pick-up discharge; and toprovide a return branch passage in advance of the timed metering devicewhich communicates with the fuel reservoir and which is calibrated toreturn to the latter that fuel admitted through the time metering devicein excess of the quantity of fuel desired in the pick-up charge.

Still further objects of the invention are to provide means in thepositive acting actuating mechanism for coupling the piston rod of thepump with the throttle control mechanism in different relations so as tovary the lengths of the strokes of the fuel displacing members; and toprovide means of this character which hold the piston rod substantiallywithin the same limits of parallelism with respect to the axis of thepump cylinder throughout the entire range of movement of the throttlecontrol mechanism regardless of the relation in which the couplingelements are united.

An illustrative embodiment of the invention is shown in the accompanyingdrawing, in which:

Fig. I is a vertical sectional view of a carburetor embodying ourinvention showing for the purpose of illustration, many of the essentialparts of the structure in a common plane.

Fig. II is a side elevation of a carburetor showing a vertical sectionof the improved pick-up pu p- Fig. III is a transverse sectional viewtaken on the line III-III of Fig. II.

In the form shown, the carburetor in which our improved pick-upmechanism is illustrated is of the up-draft type. The pick-up mechanismmay, however, be incorporated in a downdraft carburetor with equalfacility. The updraft carburetor disclosed for the purpose ofillustration includes a body portion ID in which is formed a fuelmixture passage having an air inlet I2 and an outlet l3 for deliveringfuel mixture to an intake manifold of an engine (not shown). The bodyportion III of the carburetor is provided with a fuel reservoir |4having an inlet l5 which is controlled by a valve 5. The valve I6 isoperated by conventional float mechanism I1 which predetermines the fuellevel in the reservoir.

The inlet I5 includes a coupling plug which is externally threaded in anaperture in the body portion and which is provided at its outer end withinternal threads for detachably connecting a fuel supply conduit (notshown) with the reservoir. The plug has a central passage for receivingthe valve l6 which is provided with a valve seat l6 for coacting withthe tapered end of the valve Hi. The valve may be removed andconveniently cleaned without disassembling the carburetor by merelydisconnecting the fuel supply conduit and removing the coupling plug andvalve simultaneously from the body portion of the carburetor.

Formed on one side of the carburetor is a pickup pump cylinder |8 havinga cylindrical bore |9 in which a piston 20 is slidably mounted. Theouter periphery of the piston 20 fits tightly against the innerperipheral wall of the bore 9 of the cylinder and it is provided at itscentral portion with an aperture 2| through which a reciprocating pistonrod 22 extends. Fixed on the lower end of the piston rod 22 and locatedin advance of the piston 20 is a plunger 23 including a pair of discshaving peripheries which extend to within close proximity of the:peripheral wall of the cylinder, sufficient space being provided betweenthe peripheries of the discs and the inner periphery of the cylinder topermit the passage of some of the fuel content of the cylinder from oneside to the other of the plunger during movement of the plunger in thecylinder. The piston 20 is urged toward the plunger 23 and yieldablyheld in contact with the plunger by a coil spring 24 which surrounds thepiston rod 22 and which bears at its outermost end against a metal cup25 located within the cylinder l8 and fixed to the piston rod by pin 26.

Integrally formed on the upper end of the piston rod 22 is a U-shapecoupling element 21, between the sides of which is received an arm 28 ofa throttle regulating lever 29. The lever 29 is fixed on a throttleshaft 38 journaled in apertures formed in the side walls of the fuelmixture passage II and carrying the throttle valve 3|. The throttlevalve 3| is located at the discharge end of the fuel mixture passage andis adapted to control the flow of fuel mixture to the engine with whichthe carburetor is associated. The overlapping coupling element 21 andarm 28 of the throttle control lever are each provided with a pair ofapertures 32 and 33, respectively, located at different distances fromthe axis of the throttle shaft 30. The pairs of apertures 32 and 33 areso located with respect to each other and with respect to the axis ofthe throttle shaft 30 that each aperture 32 of the element 21 willregister withvits corresponding aperture 33 of the arm 28 throughout theentire range of movement of the lever 29 while the piston rod 22 iswithin the same relation of parallelism with respect to the axis of thecylinder l8. The overlapping coupling element 21 and arm 28 arepivotally secured together by a bolt 34 which is insertable througheither set of registering apertures 32 and 33. The inner end of the boltmay be threaded in an aperture formed in the inner side of the U-shapecoupling element 21 or provided with a nut (not shown). By selectivelyplacing the bolt 34 in the innermost or outermost registering apertures32 and 33 the length of stroke of the piston rod 22 may be varied so asto predetermine the stroke of the piston and plunger with respect to afixed movement of the throttle control lever 29. Regardless of theposition of the bolt 34, the piston rod is maintained within the samerelation to the axis of the cylinder. In thissmanner excessive movementor deflection of the external end of the piston rod transversely of thelength of the piston is effectively guarded against.

The fuel reservoir M has a thick lower wall 35 in which is formed aplurality of passageways that provide a liquid fuel conveying system.. Asubstantially horizontal passageway 36 communicates with the lowerextremity of the pump cylinder 8 and has a vertical branch passage 31which leads to a substantially horizontal branch passage 38. Thehorizontal branch passage 38 communicates with the interior of the fuelreservoir l4 through an outlet port 39 which is controlled by a checkvalve 40. The check valve 40 comprises a ball which is confined in avalve casing 4| and held against downward movement by a pin 42 extendingtransversely across the valve casing. When the pick-up pump isdischarging fuel the valve 40 is held against a seat 43 formed in thevalve casing so as to prevent the return of liquid fuel to the reservoir|4 through the outlet 39 thereof. During the loading stroke of thepick-up pump, the ball valve 40 rests upon the pin 42.

The horizontal branch passageway 38 also communicates with a chamber 44in which a removable metering plug 45 is threaded. The plug 45 has acentral passage 46 leading from the interior of the'reservoir M to thehorizontal branch passage 38. This plug also has radially extendingapertures 41 extending from the central passage 46 to the chamber 44. Avalve seat 48 is formed in the central passage 46 for receiving a ballvalve 49 which prevents the return flow of fuel through the passage 46from the liquid fuel system to the fuel reservoir during the dischargestroke of the pick-up pump. The lower end of the plug 45 is providedwith a metering device 50 which controls the flow of liquid fuel fromthe horizontal branch passageway 38 to the chamber 44. The orifice ofthis metering device is calibrated to predetermine the period ofduration of the pickup discharge.

In the illustration shown, the pick-up discharge is admitted to the fuelmixture passage ll of the carburetor through a fuel nozzle 5| which alsodelivers the normal running fuel mixture to the fuel mixture passage.The nozzle 5| is threaded in a passage 52 which communicates with thechamber 44 through a branch passage 53. Threaded in the lower end of thenozzle receiving passage 52 is a plug 54 having an orifice 55 thereinfor metering the fuel content of the normal running fuel mixture.

In order to predetermine the duration of the fuel discharge it isgenerally necessary to provide the metering device 50 with an orificehavv in combination with a timed metering orifice it is possible toobtain a pick-up discharge of a desired duration and to alsoindependently predetermine the quantity of fuel in the pick-updischarge.

In operation, as the throttle valve Si is rotated toward an openposition by clockwise rotation of the throttle control lever 29, thepiston rod 22 is urged downwardly together with the plunger 23. g

The piston rod and plunger are acted upon positively by the throttlecontrol mechanism and therefore the plunger 23 simultaneously displacesfuel from the cylinder l8 with the opening of the throttle. The loosefitting relation between the plunger 23 and the provision forthe flow ofsome of the fuel around the plunger permits free movement of the plungerduring opening of the throttle, and for this reason manipulation of thethrottle control mechanism is opposed by only a slight amount of pumpresistance, thereby enabling the operator to rotate the throttle from acompletely closed to a partly open or fully open position in a shortinterval of time with'a slight degree of physical effort.

As the piston rod and plunger are moved downwardly the spring retainingcup 25 bears upon the upper end of the spring 25, tending to cause thepiston 20 to follow the plunger 23. The movement of the piston 20 is insome instances, as for example when the throttle is opened rapidly,delayed by the pressure of the fuel which flows around the periphery ofthe plunger and which has access to the working face of the piston 20.Under this condition the spring 24 yields and is placed undercompression. As the pressure under which the fuel is placed decreases byreason of the flow of the pick-up discharge through the fuel system, thespring 25 urges the piston 20 downwardly until it again engages theplunger 23. This delayed action of the piston 20 causes the pick-updischarge to continue after the throttle has come to rest in an openposition and it also enables the employment of a metering device whichhas for its sole purpose the predetermining of the duration of thepick-up discharge. By the employment of the positively actuated fueldisplacing member and the yieldably actuated fuel displacing member, weobtain an initial displacement of fuel from the pick-up systemimmediately upon opening of the throttle and an uninterruptedpick-updischarge which continues after the throttle is opened.

The fuel displaced from the pick-up pump cylinder flows through thepassageways 36, 31, and 38 underpressure sufficient to lift the ballvalves ill and 59 to closed positions so as to prevent the return flowof fuel to the reservoir I l, through the passages 39 and 45,respectively, during the discharge stroke of the pump. The fueldisplaced from the cylinder l8 passes through the orifice of the timemetering device 50, through the radial apertures 41 in the plug 45 andinto the chamber 46 from which it is conveyed by the branch passage 53to the lower end of the nozzle receiving passage 52. Some of the fuelwhich is delivered to the chamber M is returned through the meteringpassage 56 to the reservoir I 4 and the remainder, the quantity of whichis determined by the size of the passage 56, is delivered to the fuelmixture passage ll of the carburetor by the nozzle 5|. When the pick-uppump mechanism is at rest and during the loading strokes of the pick-uppump'the ball valve 49 closes the orifice of the metering device 50 andprevents the withdrawal of fuel from the nozzle 5| during the loadingstrokes of the pump.

Although but one specific embodiment of the invention is herein shownand described, it will be understood that various changes in the size,shape, and arrangement of parts may be made without departing from thespirit of our invention, and it is not our intention to limit its scopeother than by the terms of the appended claims.

What we claim is:

1. In a carburetor having a fuel mixture passage, a throttle valve forcontrolling the flow of fuel mixture from said passage having a shaftjournaled in the wall of said carburetor, a lever fixed on said shaftfor regulating said throttle valve, a cylinder having an outletcommunicating with said fuel mixture passage, a piston in said cylinderclosely fitting the inner periphery thereof, a plunger in said cylindershiftable relative to said piston andhaving a stem pivotally attached tosaid lever, said plunger being located in advance of said piston andoccupying less than the full cross-sectional area of said cylinder, anda spring having one end fixed against movement relative to said stem andits other end bearing upon said piston for yieldably urging the lattertoward said plunger.

2. In a carburetor including a fuel mixture passage and a fuelreservoir, pick-up mechanism including a pump cylinder, a liquid fuelconducting system including passageways communicating with saidcylinder, reservoir and fuel mixture passage, a fuel displacing memberin said cylinder, means including a yieldable element for urging-saidmember toward the outlet of said cylinder, a metering device in thepassageway leading from said cylinder to the passageway leading to saidfuel mixture passage for predetermining the period of duration of thepick-up discharge, a metering device in the passageway leading to thefuel mixture passage for predetermining the quantity of fuel of thepick-up discharge, and a metering passageway communicating with saidreservoir and with said fuel conducting system between said meteringdevices for returning to said reservoir the excess fuel admitted by saidfirst metering device.

3. In a carburetor including a fuel mixture passage and a fuelreservoir, pick-up pump mechanism including a pump cylinder and piston,a liquid fuel conveying system including a chamber and having fuelpassageways leading from said chamber and communicating with saidcylinder, fuel mixture passage and reservoir respectively, saidreservoir having an outlet port communicating with said cylinder, ametering device in the passageway leading from said cylinder to saidchamber for predetennining the period of duration of the pick-updischarge, and a metering device in the passageway leading to said fuelmixture passage for metering the quantity of fuel of said pick-updischarge, the passage leading from said chamber to said reservoir beingcalibrated to return to said reservoir the excess fuel admitted to saidchamber through the first mentioned metering device.

4. In a carburetor including a fuel mixture passage and a fuelreservoir, pick-up pump mechanism including a pump cylinder and apiston, a fuel nozzle communicating with said fuel mixture passagehaving a metering device therein for controlling the normal fuelmixture, a liquid fuel conveying system including a chamber and havingfuel passageways leading from said chamber to said reservoir andcylinder, said reservoir having a normal fuel outlet port communicatingwith said chamber and an outlet port communicating with said cylinderrespectively, a valve for closing the latter port during the dischargestrokes of said piston, a metering device in the passageway leading fromsaid cylinder to said chamber adjacent the normal outlet of saidreservoir for predetermining the period of duration of the pick-updischarge, and a valve for alternately closing the normal fuel outlet ofsaid reservoir and said metering device during the pickup discharge andnormal operation of said carburetor respectively, the passageway leadingfrom said chamber to said reservoir being calibrated to return to saidreservoir the fuel admitted by said pick-up discharge periodpredetermining device which is in excess of the quantity of fuel desiredin the pick-up discharge.

5. In a carburetor, pick-up mechanism including a pump cylinder, areciprocating piston in said cylinder, a piston rod having an externalend portion projecting beyond one end of said cylinder, a pivotallymounted actuating member, overlapping elements on the externalend ofsaid piston rod and on said actuating member respecv tively each havinga pair of spaced apertures therein located at different distances fromthe axis of said actuating member, each aperture of one pair beingregisterable with a corresponding aperture of the other pair throughoutthe range of movement of said actuating member and while said piston rodis within substantially the same relation of parallelism with respect tothe axis of said cylinder, and a pin insertable through correspondingapertures of said overlapping elements for pivotally connecting saidactuating member and piston rod in diverse relations so as topredetermine the length of stroke of said piston for a fixed angularmovement of said actuating member.

6. In a carburetor, pick-up mechanism including a pump cylinder, areciprocating piston in said cylinder, a piston rod having an externalend portion projecting beyond one end of said cylinder, a throttle valvein said carburetor having a rotatable shaft, a throttle and pick-up pumpactuating member on said shaft, overlapping elements on the external endof said piston rod and actuating member, each having a pair of spacedapertures therein located at different distances from the axis of saidactuating member, each aperture of one pair being registerable with acorresponding aperture of the other pair throughout the range ofmovement of said actuating member and while said piston is withinsubstantially the same relation of parallelism with respect to the axisof said cylinder, and means receivable in said apertures for pivotallyconnecting said actuating member and piston rod in diverse relations soas to predetermine the length of stroke of said piston for a fixedamplitude of movement of said throttle valve.

7. In a carburetor having a fuel mixture passage, a throttle valve insaid passage, apparatus for regulating said throttle valve, pick-up pumpmechanism including a pump cylinder, a pair of relatively movable fueldisplacing members in said cylinder, rigid actuating elements pivotallyattached to said throttle valve regulating apparatus and coactingpositively with one of said fuel displacing members for reciprocatingthe latter positively in both directions, and a yield able actuatingelement co-acting between said rigid actuating elements and the'otherfuel displacing member.

8. In a carburetor having a fuel mixture passage, pick-up mechanismincluding a pump cylin-- der having an outlet communicating with saidfuel mixture passage, positive acting mechanism including a plunger insaid cylinder for initially discharging fuel into said fuel mixturepassage, said plunger permitting some leakage of fuel thereby during itsdischarge stroke, a close fitting piston in said cylinder between saidplunger and the extremity of said cylinder opposite from its dischargeend, and a spring bearing between said piston and said positive actingmechanism for causing the latter to follow said plunger and to dischargethe fuel which passes by the latter from said cylinder.

FREDERICK 0. BALL. THOMAS M. BALL.

